A nasty, drug-resistant staph infection--the kind usually seen in hospitals--is racing across the U.S.

Jewaun Smith, a 9-year-old boy from Chicago, is lucky to be alive. A scrape on his left knee that he picked up riding his bike last October turned into a runaway infection that spread in a matter of days through the rest of his body, leaving his lungs riddled with holes. Jewaun managed to survive, but what worries doctors most about his near-death experience is that it's not an isolated case. The bacteria that infected his knee has become resistant to the most common antibiotics and is on the march across the U.S. It has spread rapidly through parts of California,...